Fix Symbol 'grub_puts' Not Found When Migrating From Ubuntu Karmic To Lucid

Alexandre from jellykernel sent us a tip he wrote on his blog (in French) about an "Fix symbol 'grub_puts' not found" error when migrating from Ubuntu 9.10 Karmic Koala to Ubuntu 10.04 Lucid Lynx, so we'll translate it into English so it hopefully helps a lot of people.